Mode of



S. B, TERRY.

Clock Escapement.

Patented Nov. 29. 1853.-

UNITED STATES" PATENT OFFICE.

SILAS B. TERRY, OF PLYMOUTH, CONNECTICUT.

MODE 0F APPLYING-THE VIBRATING SPRING OF BALANCE-CLOCKS.

Specificationof Letters Patent No. 10,277, dated November 29, 1853.

To all whom it may concern:

Be it known thatI, SILAS B. TERRY, of Terryville, Plymouth, in thecounty of Litchfield and State of Connecticut, have invented certain newand useful Improvements in Timepieces; and I do hereby declare that thefollowing is afull, clear, and exact description of the same, referencebeing 1 had to the accompanying drawings, forming part of thisspecification, in which-- Figure 1, is an isometrical view'of the escapement and balance of a. marine clock constructed according to myimprovements. Figs. 2, 3, and 4, are side views of slightly differingforms of the verge and crutch wire and spring. I

Similar letters of reference indicate corresponding parts in each of theseveral figures.

This invention is more particularly applicable to what is termed themarine clock, but is also applicable to all time pieces whose movementis governed by a balance.

It consists, first, in making what is, termed the fork or crutch wire aflat and elastic spring at, and near the end where it is attached to theverge or verge arbor, the opposite end being made small and round toenter a hole perforated in the arm of the balance wheel, or in a colleton the balance arbor, or spindle. This arbor, or spindle, is placed atright angles to the Verge arbor and in a line wit-h the crutch or forkwhere it is attached to the verge arbor. The spring part of the crutchshould be made of sufficient strength to produce the oscillations, orvibrations, of the balance, when set in motion by the motive power ofthe clock, in about such time as may be desired.

It consists, secondly, in regulating the force of the crutch spring, byincreasing or lessening its tension, in a manner substantially asfollows: 1st, by means of a screw which passes through female screws intwo cams or projections made fast to the verge arbor, and whichterminates on the crutch spring at a point near where it is fastened tothe verge arbor. 2d, by means of a screw passing, in a similar manner,through cams on the opposite side of the verge arbor, and terminatingupon a wire, which passes partly around the circumference of the colletby which the crutch spring is fastened to the verge arbor, and thence,at a little distance from the collet, comes incontact with the crutchspring on the side opposite the screw, and is hung to the collet by pinswhich permit it to move in such a direction that the pressure of thescrew will produce a strain upon the crutch spring. 3d, the colletbywhich the crutch spring is attached to the verge arbor, may be hung toit by a pin passing diametrically through both the collet and vergearbor, at right angles to the crutch wire, and the screw instead ofterminating upon the wire, as in the last instance, may terminate uponthe collet and by its pressure, strain the spring onthe opposite side ofthe verge arbor.

To enable those skilled in the art, to

make use of this invention, the following description of itspeculiarities is given, with references to the drawings hereto attached.

A, (Fig. 1,) represents the back plate of the clock; B, the escapementwheel; C, the verge; D, the verge arbor, none of which differsessentially from those in common use.

E is the crutch spring, attached to the verge shaft by means of thecollet a. This in Figs. 2, and 3, is attached firmly to the verge shaft.In Fig. 4, it is hung by the pin 6, which passes through the diameter ofthe verge shaft at right angles to the crutch spring, and allows a freemotion to the crutch spring in a plane at right angles to the axis ofthe pin 6. The crutch spring E is made of steel or other elastic'metalflattened at the part near where it is fastened to the verge shaft androunded at the other end where it enters the hole 6 in an arm of thebalance F or in a collet attached to its arbor. It is similar in form tothe crutch of the torsion spring clock for which Letters Patent No.9310, were issued to me on the 5th day of October A. D. 1852. It wasthere patented simply as a means of transmitting the motive power of theclock to the balance, and here, as taking the place of the torsion, orcommon hair spring in producing the vibrations of the balance.

The balance F is similar to the common balance, but its spindle G, ishung in a position at right angles to the verge arbor, and in a linewith the crutch spring where it is attached to the verge arbor.

(Z, (Z, are cams made fast to the verge shaft, in each of which arefemale screws which admit the regulator screw 6. This screw may as inFig. 2, terminate upon the wire f which is flattened Where it passespartly around the circumference of the collet a to which it is hung bythe pins 9, h, and comes in contact with the crutch spring E on the sideopposite to the screw; or as in Fig. 3 it may terminate directly uponthe crutch spring E; or as in Fig. 4, uponthe collet a. In either case,its effect will be, to produce more or less strain upon the crutchspring and thus, increase or lessen the vibrations of the balance. Theend of the screw opposite to the one already described may pass throughthe dial plate and there receive a hand, or pointer, the requisitedirection of whose motions may be indicated by letters upon the dial. Itwill be seen that the crutch spring moves upon a center which is in aline with the axis of the balance. Hence, the point 0, where the crutchwire enters the balance is always equally distant from the center ofmotion of the crutch spring, whatever be the position of the balancewheel when properly hung; so that there is no endwise motion of the wirein the hole a and the friction that is attendant upon the common leverescapement, is obviated.

The above described mode of applying the crutch spring to the balance ofa timepiece does not admit of a wide range of variation in the arc ofvibration, without too great a change of rate, but by trial, the arc canbe so adjusted in length as to be very nearly isochronal, 2'. 6., sothat small changes in its length of vibration will not make a materialchange of rate.

The improvement here set forth consists in the cheapness of constructionof the escapement as compared with the lever escapement and hair spring;as the parts which transmit the motive power of the clock to thebalance, and govern its vibrations, are here combined in one, and theordinary hair spring is dispensed with; likewise there is less frictionthan in the lever escapement, as the impulse imparted by the lever tothe balance is in a direct line with the motion of the balance.

What I claim as my invention, and desire to secure by Letters Patent, is

The making the crutch spring E perform the oflice of the common hairspring in producing the vibrations of the balance, substantially in themanner herein set forth.

SILAS B. TERRY.

Witnesses: 7

JOHN J. STONE, AMMI GIDDINGS.

